diff --git a/README.md b/README.md
index 7cdb83e24..9519b172a 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@ Subset of R7RS-small.
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.4.810_amd64.deb
+sudo apt install build/meevax_0.4.811_amd64.deb
 ```
 
 or
@@ -106,9 +106,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.4.810.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.4.811.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.4.810_amd64.deb`
+| `package`   | Generate debian package `meevax_0.4.811_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 34e024694..c058011d4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.4.810
+0.4.811
diff --git a/include/meevax/kernel/input_string_port.hpp b/include/meevax/kernel/input_string_port.hpp
index 068187703..d44085d21 100644
--- a/include/meevax/kernel/input_string_port.hpp
+++ b/include/meevax/kernel/input_string_port.hpp
@@ -50,7 +50,7 @@ inline namespace kernel
 
 namespace literals
 {
-  auto operator ""_read(char const*, std::size_t) -> object;
+  auto operator ""_r(char const*, std::size_t) -> object;
 } // namespace literals
 } // namespace kernel
 } // namespace meevax
diff --git a/script/unicode.sh b/script/unicode.sh
index 47dbd9c33..88ab85ce6 100755
--- a/script/unicode.sh
+++ b/script/unicode.sh
@@ -23,8 +23,8 @@ input="$(git rev-parse --show-toplevel)/configure/UnicodeData.txt"
 for each in "$@"
 do
   case "$each" in
-    --property    ) sed -E 's/^([^;]*);([^;]*;){01}([^;]*).*$/case 0x\1: return \3;/g'   "$input" ;;
-    --digit-value ) sed -E 's/^([^;]*);([^;]*;){06}([^;]*).*$/case 0x\1: return \3;/g'   "$input" | grep -e 'case 0x.\+: return .\+;' ;;
+    --property    ) sed -E 's/^([^;]*);([^;]*;){01}([^;]*).*$/case 0x\1: return   \3;/g' "$input"                                       ;;
+    --digit-value ) sed -E 's/^([^;]*);([^;]*;){06}([^;]*).*$/case 0x\1: return   \3;/g' "$input" | grep -e 'case 0x.\+: return   .\+;' ;;
     --upcase      ) sed -E 's/^([^;]*);([^;]*;){11}([^;]*).*$/case 0x\1: return 0x\3;/g' "$input" | grep -e 'case 0x.\+: return 0x.\+;' ;;
     --downcase    ) sed -E 's/^([^;]*);([^;]*;){12}([^;]*).*$/case 0x\1: return 0x\3;/g' "$input" | grep -e 'case 0x.\+: return 0x.\+;' ;;
   esac
diff --git a/src/kernel/input_string_port.cpp b/src/kernel/input_string_port.cpp
index 6b6bad0cb..e4deb5860 100644
--- a/src/kernel/input_string_port.cpp
+++ b/src/kernel/input_string_port.cpp
@@ -46,7 +46,7 @@ inline namespace kernel
 
 namespace literals
 {
-  auto operator ""_read(char const* s, std::size_t) -> object
+  auto operator ""_r(char const* s, std::size_t) -> object
   {
     return input_string_port(s).read();
   }
diff --git a/src/main.cpp b/src/main.cpp
index 3db9f8fff..a629f9cb6 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -25,31 +25,31 @@ auto main(int const argc, char const* const* const argv) -> int
 
   return with_exception_handler([&]()
   {
-    auto interact = [&](auto & environment)
+    auto interact = [&](environment & e)
     {
-      if (environment.configure(argc, argv); environment.interactive)
+      if (e.configure(argc, argv); e.interactive)
       {
-        environment.import("(scheme base)"_read);
-        environment.import("(scheme case-lambda)"_read);
-        environment.import("(scheme char)"_read);
-        environment.import("(scheme complex)"_read);
-        environment.import("(scheme cxr)"_read);
-        environment.import("(scheme eval)"_read);
-        environment.import("(scheme file)"_read);
-        environment.import("(scheme inexact)"_read);
-        environment.import("(scheme lazy)"_read);
-        environment.import("(scheme load)"_read);
-        environment.import("(scheme process-context)"_read);
-        environment.import("(scheme read)"_read);
-        environment.import("(scheme repl)"_read);
-        environment.import("(scheme time)"_read);
-        environment.import("(scheme write)"_read);
+        e.import("(scheme base)"_r);
+        e.import("(scheme case-lambda)"_r);
+        e.import("(scheme char)"_r);
+        e.import("(scheme complex)"_r);
+        e.import("(scheme cxr)"_r);
+        e.import("(scheme eval)"_r);
+        e.import("(scheme file)"_r);
+        e.import("(scheme inexact)"_r);
+        e.import("(scheme lazy)"_r);
+        e.import("(scheme load)"_r);
+        e.import("(scheme process-context)"_r);
+        e.import("(scheme read)"_r);
+        e.import("(scheme repl)"_r);
+        e.import("(scheme time)"_r);
+        e.import("(scheme write)"_r);
 
         while (standard_input_port().good())
         {
           try
           {
-            std::cout << u8"\u03bb> " << environment.evaluate(standard_input_port().read()) << std::endl;
+            std::cout << u8"\u03bb> " << e.evaluate(standard_input_port().read()) << std::endl;
           }
           catch (error const& error)
           {